The present invention relates to a composite toothpaste product containing a fluorine compound and a hydroxyapatite in combination. In particular, the invention relates to an improved composite toothpaste product which imparts favorable effects to teeth by way of the activity of the fluorine compound as well as the activity of the hydroxyapatite, when the teeth are brushed.
The toothpaste generally comprises water, a wetting agent, and an abrasive. Until now, proposals to incorporate a variety of additives into the toothpaste for improving functions of the toothpaste have been made. Some of these proposals have been employed in the production of commercially available toothpastes.
A representative additive is a fluorine compound. It has been confirmed that a fluorine compound is dissociated in an aqueous toothpaste to give a fluorine ion which reacts with a surface layer of the tooth to enhance the surface hardness of the tooth. A toothpaste containing a fluorine compound is described in Japanese Patent Provisional Publication No. 46-4150.
Recently, incorporation of a hydroxyapatite having the same chemical composition as that of the tooth into a toothpaste has been studied. The incorporation of a hydroxyapatite is described in Japanese Patent Provisional Publications No. 55-57514, No. 56-73014, No. 56-73015, No. 60-206678, No. 61-91333, and No. 57-185213. Since the hydroxyapatite has the same chemical composition as that of tooth, it has a high affinity to the tooth and can be attached to a defective portion of tooth produced by dental caries when it is incorporated into a toothpaste. Further, the hydroxyapatite is effective for removing a bacterial plaque attached to the tooth. For these reasons, a toothpaste containing a hydroxyapatite is commercially available.
As described above, each of a fluorine compound and a hydroxyapatite imparts to a toothpaste an additional performance. Therefore, it has been studied to incorporate both chemicals in combination into toothpastes. It has been noted, however, that a fluorine compound is highly reactive to a hydroxyapatite and the incorporation both chemicals into a toothpaste causes a reaction between them to produce a fluorinated apatite or a calcium fluoride which is very hard. Accordingly, the performances of the both chemicals cannot be utilized in the toothpaste.
Japanese Patent Provisional Publication No. 58-219107 proposes to prepare a fluorine ion source and a calcium ion source (no hydroxyapatite is mentioned) separately and to utilize them sequentially or simultaneously when teeth are brushed.
Japanese Patent Provisional Publication No. H1-6213 (which corresponds to Japanese Patent Publication (examined) No. H2-31049) discloses a toothpaste which comprises microcapsules containing a hydroxyapatite (or a fluorine compound) and a supporting material containing a fluorine compound (or a hydroxyapatite) in which the microcapsules are dispersed.
The present inventors studied these known composite toothpaste products and noted that these products hardly give to the toothpastes the target combined effects. In more detail, the composite toothpaste product of Japanese Patent Provisional Publication No. 58-219107 requires two toothpastes which should be encased in different vessels and which are necessarily employed in combination when teeth are brushed. In the microcapsuled toothpaste of Japanese Provisional Publication H1-6213, the wall of the microcapsule is sometimes not enough for reliably separating the fluorine compound from the hydroxyapatite, and therefore the reaction between both chemicals possibly proceeds during storage of the toothpaste product. If the wall of the microcapsule has an increased thickness, the reaction is effectively obviated. In that case, however, the microcapsules are hardly broken in the brushing procedure and the performance of the microcapsuled chemical is hardly utilized.
Further studies by the present inventors have revealed that when a fluorine compound and a hydroxyapatite are simultaneously employed in the teeth brushing procedure and the fluorine compound is first brought into contact with teeth, the teeth rapidly react with the fluorine compound to form a hard surface layer thereon and hence the desired contact of the hydroxyapatite to the teeth is disturbed. Moreover, it has been noted that a fluorine compound is preferably brought into contact with teeth after the teeth are covered with a hydroxyapatite so that the effect of hardening tooth surface to be provided by a fluorine compound can not be attained.
The present invention resides in a composite toothpaste product comprising a toothpaste containing a hydroxyapatite as a main active ingredient and another toothpaste containing a fluorine compound as a main active ingredient, which are enclosed with a container but separated from each other by a partition united to the container, under the condition that these toothpastes are separated from each other with no contact when it is out of use, and are squeezed out of the container, when in use, in such a manner that the latter toothpaste is enclosed with the former toothpaste.
The above-mentioned composite toothpaste product of the invention preferably has such a structure that the container comprises double tubes in which one is an outer flexible tube having one open end and another is an inner flexible tube having one open end, the open end of the inner tube being put back from the position of the open end of the outer tube in the longitudinal direction of the tubes, the toothpaste containing a fluorine compound being placed in the inner tube, and the toothpaste containing a hydroxyapatite being placed in a space formed between the inner tube and the outer tube.
In the invention, the hydroxyapatite is preferably contained in the toothpaste containing an hydroxyapatite in an amount of 1 to 30 weight %, based on the total amount of the toothpaste containing an hydroxyapatite and the toothpaste containing a fluorine compound, and the fluorine compound is preferably contained in the toothpaste containing a fluorine compound in an amount of 0.002 to 2.0 weight % in terms of an amount of fluorine ion, based on the total amount of the toothpaste containing an hydroxyapatite and the toothpaste containing a fluorine compound. It is also preferred that the fluorine compound is contained in the toothpaste containing a fluorine compound in an amount of 0.001 to 3.0 weight % in terms of an amount of fluorine ion, based on the amount of the hydroxyapatite contained in the toothpaste containing an hydroxyapatite.